Although the major goal of the Epidemiology Section is the development of a vaccine against Group (Gp) A rotavirus, it is important to study other antigenically distinct groups of rotavirus (B-G) since viruses belonging to two of these groups, B and C, have been implicated as etiologic agents of diarrheal disease in humans. Group B rotaviruses have been associated with large outbreaks of severe diarrhea in adults. Curiously, these outbreaks have, thus far, remained limited to China. Sporadic outbreaks and isolated cases of diarrhea caused by Group C rotavirus have been reported in several countries and this group of agents appears to be associated with illness in an older population of children (school-aged) than that of group A rotaviruses (6 months to 2 years of age). It has been difficult to establish the epidemiology of the "non-group A" human rotaviruses because they cannot be cultivated in cell culture, making the development of reagents for diagnostic tests difficult. One objective of this project is to generate tools for epidemiologic studies. However, it is also of interest to examine the molecular basis for group differences among rotaviruses because it may give insight into the mechanisms that have caused Group A rotaviruses to predominate as an enteric pathogen.